Recent research suggests that chemicals used to protect, process and package food could be helping to create fat cells.

Obesity, it would seem, is one big “My bad,” a painfully visible failure in personal responsibility. If you regularly chow down a pizza and a pint of ice cream for dinner, and your idea of a vigorous workout is twisting off caps on two-liter bottles of Coke, well, it’s pretty hard to give yourself a pass for packing on pounds.

Certainly, most doctors and dieticians still believe that being overweight is a matter of too many calories in, and not enough calories out, or put more bluntly, way too much food and way too little exercise. It’s all about overconsumption, right? End of story.

Except the plot appears to be thickening.

Recent research is beginning to suggest that other factors are at work, specifically chemicals used to treat crops and to process and package food. Scientists call them obesogens and in one study at the University of California, Irvine, they caused animals to have more and larger fat cells. ”The animals we treat with these chemicals don’t eat a different diet than the ones who don’t get fat,” explained lead researcher Bruce Blumberg. “They eat the same diet–we’re not challenging them with a high-fat or a high-carbohydrate diet. They’re eating normal foods and they’re getting fatter.”

The theory is that the chemicals disrupt hormonal systems and that can cause stem cells to turn into fat cells. In other words, the thinking goes, obesogens may help flip your fat switch.

But before you cleanse yourself of all responsibility for your tight-fitting clothes, keep in mind that plenty of researchers bristle at the suggestion that anything other than excess calories is to blame. In fact, a much-cited, recent study led by George Bray of Louisiana State University found that any diet can work so long as calories consumed are consistently reduced. Said Bray: “Calories count. If you can show me that it (the calories in, calories out model) doesn’t work, I’d love to see it.”

And yet, Kristin Wartman, writing on The Atlantic website, raises a provocative notion: “If the obesogen theory comes to be accepted… the food industry will be in trouble. It would be harder to keep promoting diet and “health” foods that may be low in calories but that also contain an array of substances that may actually prove to contribute to weight gain.”

Now that could get ugly.

More is less

Another new study on obesity does its own number on conventional thinking. Most of us likely think that we overeat because we love every bite. Not so, say Kyle Burger and Eric Stice at the Oregon Research Institute. They found that when we eat too much, it’s because we’re actually getting less pleasure from the food, so we have to consume more to feel rewarded.

The pair reached this conclusion through the use of a classic combo: teenagers and milkshakes. Based on brain scans done on the slurping adolescents, they determined that the ones who ate the most had the least activation of dopamine neurons, which generate pleasurable feelings. To compensate, they had to eat more.

But help may be on the way for eaters who can’t get no satisfaction. Later this spring the FDA is expected to approve a new drug called Qnexa. It both increases the pleasure of food and reduces the desire to keep eating.

Weight, weight, don’t tell me

Here’s more recent news from the fat front:

Walk the walk: A study presented at the American Heart Association conference in San Diego yesterday concluded that people could overcome a genetic predisposition to obesity by walking briskly for an hour a day. By contrast, people with obesity in their families who watched television four hours a day were 50 percent more likely to carry on the weighty tradition.

You’ll have to pry my Big Gulp from my cold, dead hands: Hawaii recently became the latest state to reject a proposal to impose a tax on soda. Over the past few years, Coca-Cola, Pepsi and the American Beverage Association have spent an estimated $70 million to lobby against these soda taxes, designed to get people to drink less sweet stuff.

Do these genes make me look fat? Scientists in Japan discovered a genetic mutation that could make people more likely to become obese if they eat a high-fat diet.

Expensive tastes: A study of 30,000 Medicare recipients showed that the health care costs of overweight people increased almost twice as much as those with a more normal body mass index. Also, according to Gallup research, Americans paid around $80 billion for additional health care costs related to obesity in 2011.

How about a little fudge for breakfast? Okay, let’s end on an upbeat note. A study in Israel found that starting the day with a full meal that includes a sweet dessert makes it easier for people to stick to a weight-loss program.